Nicotine may have a therapeutic effect in patients with neurodegenerative brain diseases.

An excerpt from the article 15 facts about nicotine

This is because nicotine affects not only acetylcholine but also other neurotransmitters, especially dopamine, which is lacking in Parkinson's disease. In patients suffering from this disease, nicotine reduces the occurrence of involuntary body movements - a typical symptom of this disease - by up to one-third.